INSULIN‐LIKE GROWTH FACTOR 1 AND BONE TURNOVER IN GLUCOCORTICOID‐TREATED AND CONTROL SUBJECTS

Abstract
SUMMARY: The role of the growth hormone‐somatomedin axis in the genesis of steroid osteoporosis has been studied by measuring circulating insulin‐like growth factor I (IGF‐1) levels in asthmatic subjects either receiving or not receiving therapy with oral glucocorticoids. There was no difference in IGF‐1 levels between the two groups (60.6 μg/l (95% confidence interval 47.3–77.8) in the control subjects vs 69.1 μg/l (49.3–96.9) in the steroid‐treated group). IGF‐1 declined with age in the control subjects but not in those taking steroids. When IGF‐1 levels were correlated with biochemical indices of bone turnover, a significant relationship was found with urine hydroxyproline in the control subjects (r=0.55, P) but not in those taking steroids. It is concluded that glucocorticoid therapy does not alter mean circulating levels of IGF‐1 but that the growth hormone‐somatomedin axis may influence bone turnover in normal subjects. Interference by glucocorticoids with the normal regulation of IGF‐1 and its influence on bone turnover is suggested.